All United States Patents referred to herein are hereby incorporated by reference in their entireties. In the case of conflict, the present specification, including definitions, will control.
Numerous methods and devices are known and available for stabilizing and fixating bone fractures in various bone types in an individual. These include both external and internal fixation systems. For example, U.S. Pat. No. 6,682,561 refers to an implantable spinal, vertebral replacement device that includes a tubular cage and a series of plates and screws. Other spinal stabilization systems used in posterior spinal fusions also involve plate and screw constructs. Such systems are limited in their effectiveness in that screw placement depends on the locations of the plate holes. As a result, screws are placed in sub-optimal locations and at sub-optimal angles that could threaten neurovascular injury and compromise fracture fixation. Recent spinal stabilization techniques have employed modular rod and screw systems that allow more flexibility in screw placement, by permitting the screws to be placed first, after which they are affixed to a common rod.
Various other systems exist for fixating bones. U.S. Pat. No. 6,660,009 refers to nails and a nail insertion device used in the fixation of distal radial fractures. U.S. Pat. No. 6,692,496 refers to an internal fixation device that employs the axial insertion and anchoring of elongate members into long bones to treat fractures.
U.S. Pat. No. 6,585,736 refers to external fixation of a fractured radius using a variety of components, including rods, pins, clamps, and sliding plates. U.S. Pat. No. 6,716,212 refers to an external rod and clamp construct for use in immobilizing or stabilizing unexposed long bone fractures in patients who are unable to undergo definitive fixation. The system involves percutaneous pins placed through stab incisions, which pins are then fastened to external rods.
The fixation of certain fractures, such as comminuted intra-articular fractures in the appendicular skeleton, is not adequately addressed in the art. Important considerations in fixating such fractures include the need for proper anatomic alignment and rigid fixation. Current fixation techniques typically rely upon the use of plates and screws once an anatomic reduction has been achieved. These plate systems do not allow for flexibility in screw placement, which is necessary for achieving optimal interfragmentary fixation. Often, screws are used outside of the plate construct in order to augment fixation.
FIG. 1 illustrates a typical internal fixation device used in the art, which exhibits the above inadequacies. In this figure, the device is employed in an effort to fixate fractures 20 in a bone 10. The fractures have resulted in several fragments 30 being present. This device involves one or more plates 40 which have within them a series of holes 50 for securing the plates to the bone using screws 60. As can be seen from the figure, the placement of the screws is entirely dictated by the locations of the holes in the plates. These limitations in screw placement, including the angle in which the screw can be inserted, frequently result in anatomically inadequate or inappropriate placement of screws, which can lead to improper fixation, limited effectiveness in healing, limited range of motion, and damage or disruption to nerves or vessels.
Recent advances in plate fixation systems have incorporated locking screw designs in which the screw head threads into the plate, providing a fixed-angle screw-plate construct. This concept, adapted from anterior spinal instrumentation systems, has increased the rigidity of the overall construct and the pull-put strength of the screws, but at the cost of further limiting angular screw positioning.
There is thus a need in the art for a system and method that mitigates or eliminates the above disadvantages and inadequacies seen in the art, while maximizing the advantages of rigidity via fixed angle devices. In particular, there is a need for a system and method for providing a strong, rigid bone fixation in a manner that is anatomically appropriate for the individual.